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首页> 外文期刊>Journal of geophysical research. Solid earth: JGR >Earthquake Initiation From Laboratory Observations and Implications for Foreshocks
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Earthquake Initiation From Laboratory Observations and Implications for Foreshocks

机译：从实验室观察和对前击的影响的地震开始

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摘要

This paper reviews laboratory observations of earthquake initiation and describes new experiments on a 3-m rock sample where the nucleation process is imaged in detail. Many of the laboratory observations are consistent with previous work that showed a slow and smoothly accelerating earthquake nucleation process that expands to a critical nucleation length scale L_c, before it rapidly accelerates to dynamic fault rupture. The experiments also highlight complexities not currently considered by most theoretical and numerical models. This includes a loading rate dependency where a “kick” above steady state produces smaller and more abrupt initiation. Heterogeneity of fault strength also causes abrupt initiation when creep fronts coalesce on a stuck patch that is somewhat stronger than the surrounding fault. Taken together, these two mechanisms suggest a rate-dependent “cascade up” model for earthquake initiation. This model simultaneously accounts for foreshocks that are a by-product of a larger nucleation process and similarities between initial P wave signatures of small and large earthquakes. A diversity of nucleation conditions are expected in the Earth's crust, ranging from slip limited environments with L_c < 1 m, to ignition-limited environments with L_c > 10 km. In the latter case, L_c fails to fully characterize the initiation process since earthquakes nucleate not because a slipping patch reaches a critical length but because fault slip rate exceeds a critical power density needed to ignite dynamic rupture.
机译：本文评论了地震启动的实验室观察，并描述了在3米岩石样品上进行了新的实验，其中详细成熟了核成果。许多实验室观察结果与之前的工作符合，显示出慢速且平稳地加速的地震成核过程，该过程扩展到临界成核长度尺度L_C，然后迅速加速到动态故障破裂。该实验还突出了目前未被大多数理论和数值模型考虑的复杂性。这包括加载速率依赖性，其中“踢动”高于稳态产生较小且更突然的发起。当蠕动前线的夹持贴片上的碎片弯曲时，故障强度的异质性也会导致突然发起，这些贴片比周围的故障有点强。连同，这两种机制建议了地震启动的速率依赖性“级联”模型。该模型同时占GOOSHOCK的副产品，其较大的小地震初始P波签名之间的较大成核过程和相似之处。在地壳中，预期成核条件的多样性，从L_C <1米的滑动有限环境范围内，以L_C> 10公里点燃限量环境。在后一种情况下，L_C无法完全表征启动过程，因为地震核心不是因为滑动贴片达到临界长度，但由于故障滑移率超过点燃动态破裂所需的临界功率密度。

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